Cavernoma gigante: relato de dois casos Giant cavernous angioma: report of two cases

Angiomas cavernosos ou hemangiomas ou ainda cavernomas são malformações do sistema nervoso central, classificadas como lesões cerebrais vasculares ocultas, frequentemente assintomáticas, sendo relativamente raras. Definidas histologicamente como massas compactas cavernosas ou canais sinusoidais de vários tamanhos, com paredes finas no interior do parênquima cerebral e sem intervenção do tecido glial. Podem ocorrer em qualquer faixa etária inclusive em neonatos. Na maioria das vezes são lesões de tamanho reduzido, localizadas no interior do parênquima encefálico. Angiograficamente não mostram alterações com circulação patológica, podendo mesmo não ser diagnosticados pela tomografia, sendo o exame ideal para o seu diagnóstico a ressonância magnética de crânio. Os cavernomas são lesões histologicamente benignas mas, dependendo de sua localização, podem trazer grandes transtornos neurológicos e ser irressecáveis. A exérese cirúrgica da lesão é o tratamento de escolha se a lesão for única e em localização favorável e estiver desencadeando sintomatologia neurológica prejudicial ao paciente. Apresentamos dois casos de cavernomas gigantes que apresentaram boa evolução após ressecção cirúrgica completa. Descritos como gigantes, foram encontrados apenas três casos individuais na literatura .<br>Cavernous angiomas or haemangiomas or yet cavernomas are malformations of the central nervous system classified as occult vascular brain lesions. These rare lesions are clinically silent. They are defined by the presence of abnormally large vascular cavities or sinusoids channels of variable size, with sharp walls, located inside but not invading the brain parenchyma. They can occur at any age, including the neonatal period. Most of the small lesions are located inside the brain parenchyma. No abnormal circulation can be demonstrated in angiography and CT scan can be helpful for diagnosis only in rare occasions. Magnetic resonance is the best exam to demonstrate the lesion. Despite the benign character some lesions may cause neurologic dysfunction when their removal may be difficult. Complete extirpation is the best treatment if the lesion is favorable located and is causing neurological dysfunction. Two cases of giant cavernomas with good outcome after total removal are present. Only three cases of giant cavernomas were reported in the literature

What makes a planet habitable?

This work reviews factors which are important for the evolution of habitable Earth-like planets such as the effects of the host star dependent radiation and particle fluxes on the evolution of atmospheres and initial water inventories. We discuss the geodynamical and geophysical environments which are necessary for planets where plate tectonics remain active over geological time scales and for planets which evolve to one-plate planets. The discoveries of methane–ethane surface lakes on Saturn’s large moon Titan, subsurface water oceans or reservoirs inside the moons of Solar System gas giants such as Europa, Ganymede, Titan and Enceladus and more than 335 exoplanets, indicate that the classical definition of the habitable zone concept neglects more exotic habitats and may fail to be adequate for stars which are different from our Sun. A classification of four habitat types is proposed. Class I habitats represent bodies on which stellar and geophysical conditions allow Earth-analog planets to evolve so that complex multi-cellular life forms may originate. Class II habitats includes bodies on which life may evolve but due to stellar and geophysical conditions that are different from the class I habitats, the planets rather evolve toward Venus- or Mars-type worlds where complex life-forms may not develop. Class III habitats are planetary bodies where subsurface water oceans exist which interact directly with a silicate-rich core, while class IV habitats have liquid water layers between two ice layers, or liquids above ice. Furthermore, we discuss from the present viewpoint how life may have originated on early Earth, the possibilities that life may evolve on such Earth-like bodies and how future space missions may discover manifestations of extraterrestrial life